The short answer
- Open the Prism ZIP in Splitlight. Each project gets its own Overleaf ZIP, with the files at the top and the build files (.aux, .log and the like) left out.
- In Overleaf: New project > Upload project, and choose that ZIP.
- If Splitlight shows Part 1 of 2 (or more), upload part 1 as the new project. It holds every .tex, .bib and style file. Then add the other parts' files inside the project, as described below.
- Check Menu > Main document and Menu > Compiler. Splitlight tells you both for each project.
Overleaf's limits
| Limit | Free plan | Paid plans |
|---|---|---|
| One upload | 50 MB, 180 files | 50 MB, 180 files |
| Files per project | 2,000 | 2,000 |
| Editable text per project | 7 MB | 7 MB |
| One editable text file | 2 MB | 2 MB |
| Compile time | 10 seconds | 240 seconds |
Overleaf's upload help says plainly what happens past 180 files: "only 180 files will be uploaded". The rest are dropped without a second warning, which is how a thesis arrives with half its figures. For a ZIP over 50 MB its advice is to upload part of the files to create the project and add the rest by hand. Splitlight builds those parts for you.
A project too large for one upload
- Upload part 1 with New project > Upload project.
- Unzip part 2 on your computer. It keeps the project's folders, for example
figures/. - In Overleaf's file tree, select the folder of the same name (make it with New folder if it is not there), choose Upload, and pick that folder's files from part 2. Overleaf's help says a chosen folder keeps its structure, so you can also pick the folder itself.
- Repeat for each part, 180 files at a time.
Splitlight also lists figures that no document uses (no \includegraphics line names them). Leaving those out can bring a project back under the limits. A figure built from a macro, like \includegraphics{\figdir/plot}, cannot be traced, so check before you delete anything.
Three errors that are not about size
- The wrong main document. Overleaf guesses which
.texto compile. A project with a response letter or a supplement next to the paper may get the wrong one; set it under Menu > Main document. - fontspec requires XeTeX or LuaTeX. New Overleaf projects compile with pdfLaTeX. A project that loads
fontspec,unicode-mathorpolyglossianeeds Menu > Compiler > XeLaTeX or LuaLaTeX. - File not found, though it is there. Overleaf compiles on Linux, where
Overview.pngandoverview.pngare different files. Splitlight flags every name that matches only when letter case is ignored.
The free plan's 10-second compile limit can stop a long thesis even when every file is present. Compiling one chapter at a time with \includeonly, or turning large PNG figures into PDF or JPG, keeps it shorter.
Moving more than one project? Open the whole Prism ZIP here and download each project ready for Overleaf. Nothing is uploaded.
Open your export in SplitlightSplitlight Pro, $8 paid once: the whole export sorted in one ZIP, with every project ready for Overleaf, every document as one .tex, every chat as Markdown and a spreadsheet of the projects. Get Pro on Gumroad or see what is free.
Questions
How do I upload a Prism project to Overleaf?
Export it from Prism as a ZIP, then in Overleaf choose New project, Upload project. If the ZIP holds several projects or the files sit inside a folder, open it in Splitlight first to get one ZIP per project with the files at the top.
Why did only part of my Prism project upload to Overleaf?
Overleaf takes at most 180 files in one upload, and its help says only 180 are uploaded when there are more. Split the project into parts; Splitlight makes them.
What is the Overleaf upload size limit?
50 MB per upload, on free and paid plans. A project itself can grow larger by uploading in parts; Overleaf recommends staying under 500 MB.
Why does my Prism project say fontspec requires XeTeX or LuaTeX on Overleaf?
Overleaf starts new projects on pdfLaTeX. Change Menu, Compiler to XeLaTeX or LuaLaTeX, the engine the project was written for.
Sources
- Overleaf documentation: Plan limits. Compile timeout (10 seconds free, 240 paid), 2,000 files per project, 7 MB of editable material, 2 MB per editable file, 50 MB per upload
- Overleaf documentation: Uploading a project. "Each upload can contain up to 180 files", the 50 MB workaround, and moving files out of a top-level folder so the main document is found
- Overleaf documentation: Uploading files to a project. "a hard limit of 180 individual files per upload and 50 MB of data per upload"; a chosen folder keeps its structure
- OpenAI Help Center: Prism to Codex migration guide (article 20001615). The export steps, export-errors.json, what does not move with the files, and the note on Codex's built-in LaTeX compiler. Read through search results and quotes, as the page refuses automated readers
Last checked: October 30, 2026.